No problem, let's work through this together. We're starting with 728 and 3171 and adding them all up.

Step 1: We'll start by adding the digits 8 & 1 in column 1 and get 9.

Step 2: We'll start by adding the digits 2 & 7 in column 2 and get 9.

Step 3: We'll start by adding the digits 7 & 1 in column 3 and get 8.

Step 4: We'll start by adding the digits 0 & 3 in column 4 and get 3.

So, 728 + 3171 = 3899.

